The aim of the investigations described in this application is to study changes in energy metabolism taking place in the antral, corpus and fundic regions of the gastric mucosa of rabbits subjected to hemorrhagic shock during which the mean arterial blood pressure will be maintained at a predetermined level. In another set of experiments the time-course of gross and microscopic lesions produced in the gastric mucosa by the same degree of hemorrhagic hypotension will be followed and correlated from the standpoint of location and severity with the biochemical changes (tissue levels of ATP, ADP and AMP and of other substrates) reflecting energy metabolism. The latter will also be compared with similar changes taking place in the liver and skeletal muscle under the same conditions.